A318987 Number of semigroups of order n without identity.

1, 0, 3, 17, 153, 1687, 26397, 1596113, 3682361420

Offset

0,3

Links

Table of n, a(n) for n=0..8.

Index entries for sequences related to semigroups

Formula

a(n) = A027851(n) - A058129(n).

Crossrefs

Cf. A027851, A058129.

Sequence in context: A020562 A193161 A364630 * A353258 A208832 A377810

Adjacent sequences: A318984 A318985 A318986 * A318988 A318989 A318990

Keyword

nonn,more

Author

Steve Szabo, Sep 06 2018

Extensions

More terms from Joerg Arndt, Dec 09 2018

a(0) prepended by Jianing Song, Oct 26 2019

Status

approved